Skip to main content

Reply to this post | See parent post | Go Back
View Post [edit]

Poster: BlueMtnMan Date: Jun 2, 2007 2:42pm
Forum: GratefulDead Subject: Re: VBR and 64 kbps

Guys, there is some misinformation being posted on this topic. Not a certified audiophile, but I'll try to clear a few misconceptions.

There is virtually no audible difference between quality encoded mp3s and lossless. The mp3s say at Speeding Arrow tested in an ABX test against their lossless counterpart are undetectable. Don't believe me? Do your own ABX test. I was humbled and had to rethink my lossless snobbery. MP3s can even be traded as long as one uses data discs and not audio discs. Check out this link for more info on mp3 encoding: http://wiki.hydrogenaudio.org/index.php?title=LAME

There is a huge difference between VBR and 64KBS CBR. A VBR setting allows you to set the encoder for quality preference not file size. To create transparent mp3 files, the necessary quality setting produces files averaging between 170-210KBS. The actual size used varies as the complexity of the music varies. More complex samples require more bitrate to properly encode. 64KBS is a CBR (constant bitrate) setting that forces the encoder to use 64 KBS. This is way below the transparent range for mp3s. Good enough maybe for a car stereo with your windows rolled down and a leak in your muffler.

If you ever convert mp3s to wav do not re-encode them back to mp3. The expansion of the mp3 back to wav does not put back all that was removed when the mp3 was first encoded. The wav can not be any better than the mp3 which created it. Re-encoding back to mp3 or any other lossy file format chops more out. The resulting file can be no better than the original mp3 and is possible noticible deterioration will occur.

Reply to this post
Reply [edit]

Poster: fireeagle Date: Jun 2, 2007 4:06pm
Forum: GratefulDead Subject: Re: VBR and 64 kbps

bmm-

i convert mp3s to vaw and burn them on audio cds. the volume, the clarity and general quality of the sound are definitely very much increased compared to original mp3s

example (my last year´s favourite show):
http://www.archive.org/details/paf2006-06-25.neumann.admkrk.35452.sbeok.flac16
I dl´d mp3(64kbps/size-86mb) > converted to wav(1411kbps/size-1.71gb) > burned it to audio cdr. the resulting sound just blew my mind and almost blew my speakers, man. no comparison with original mp3s

as for converting wav back to mp3, i never done that before, but when veblen asked i did choose one wav file( cold rain and snow 69-11-02) - 705kbps/29,9mb and converted it back to mp3 - 64kbps/2,8mb. the size and the sound were identical to the mp3 file i originally dl´d

i don´t claim to be an expert on the subject, but i do believe my ears

peace

(~):-)



Reply to this post
Reply [edit]

Poster: tigerbolt Date: Jun 2, 2007 4:13pm
Forum: GratefulDead Subject: Re: VBR and 64 kbps

Every time you encode with a lossy encoder, the quality will decrease. There's no way to gain quality back even if you transcode your 128kbps MP3 into a 320kbps MP3 (or any other high-quality compression).

Transcoding between lossy formats is therefore generally not recommended. The sound quality of the result will always be worse than the (lossy) source file. Reasons to use this approach anyway could be:

* Lowering the bitrate for use in portable players, for which a listener may not care so much about sound quality.
* Saving storage space. Raw CD-audio data is about 1411 kbps (605 MB per hour); lossless encoders achieve around 700 kbps (300 MB/h). Lossy encoders such as Vorbis, MPC, and AAC achieve transparency for most people at 150--170 kbps (69 MB/h). For MP3 (with the LAME encoder), transparency is usually achieved around 192 kbps (82 MB/h). For a large music collection, this could make a significant difference in disk space as compared to lossless archiving.

Lossy transcoding has been discussed in a few forum threads:

* Transcoding to mp3 - Listening test by guruboolez, from 256 kbps lossy to 128 kbps mp3. According to this test, Ogg Vorbis and MPC performed best, followed by WV4 and AAC with a marginal difference. Transcoding from 256 kbps MP3 to 128 mp3 caused a very significant deterioration compared to 128 kbps mp3 directly from the original.
* 192 kbps Ogg to 128 kbps Ogg Remark that this is a bad idea, although apparently without thorough ABX testing.
* Transcoding from 192 kbps (preset standard) mp3. Informal subjective findings (no ABX test) with classic rock music: Ogg 96 or 128 kbps are audibly different from the source mp3, but still acceptable. Mp3 and WMA at 128 kbps had an unacceptable deterioration. AAC 96 kbps was better than Mp3 and WMA, but still had objectionable artifacts.
* Mp3 to Ogg Ogg -q6 was required to achieve transparency against the (high-quality) mp3 with difficult samples.

[edit] Lossless-to-lossless transcoding

Unlike the aforementioned lossy transcoding, quality will not decrease. Thus you may transcode from one lossless format to another as often as you like (e.g. to take advantage of better compression or better error-correction or better hardware support).
[edit] Lossless-to-lossy transcoding

Keeping lossless archives gives you the opportunity to re-encode music in the future to other lossy formats as encoder technology improves. For example, if currently lossy format X is transparent at 192 kbps, while in three years lossy format Y is transparent at 128 kbps, it is still not likely that transcoding from X@192 to Y@128 will give acceptable results, contrary to transcoding from lossless. This is due to the fact that X, being lossy, already removes some information it considers unimportant, but which in fact is important for Y. The result is Y's encoding will be greatly maimed.

If you are transcoding to lossy encoding from a lossless source, it is strongly recommended to keep the lossless source files. Thus, if the lossy result is not satisfactory, you can reencode easily.

Note that some transcoding tools have the option to automatically delete source files. Make sure that this option is turned off.i have no problems with mp3 for personal use for ipods and other portable devices but strongly against it be used as trading,stick to the original lossless format for trading.the guy at speeding arrow i'm sure has all his shows on hard drives or dvd in shn/flac files.

Reply to this post
Reply [edit]

Poster: veblen Date: Jun 2, 2007 3:32pm
Forum: GratefulDead Subject: Re: VBR and 64 kbps

THANKS BlueMtnMan!!!

I shall take a look the link; and I am not feeling so bad about the conversions that I have done.